program Project2;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  i, n0, n, x0, y0 : integer;
  x, y, p : real;

begin
  x0:=1;
  y0:=1;
  randomize;
  n:=0;
  n0:=0;
  for i:= 0 to 100000000-1 do
  begin
    x:=2*random;
    y:=2*random;
    if ((x-1)*(x-1)+(y-1)*(y-1)<=1) then
      n0:=n0+1;
    n:=n+1;
  end;
  p:=(4*n0)/n;
  writeln(p:0:9);
  readln;
end.
 